Antifungal Activity of Endophytic Fungal Species Isolated from Apple (Malus domestica)
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Date
2016
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Uva Wellassa University of Sri Lanka
Abstract
Novel natural metabolites with a microbial origin are one of the most interested areas in Natural Product Chemistry. This study was aimed to investigate the antifungal activity of endophytic fungal species isolated from apple (Malus domestica). Endophytes, which have a microbial origin, reside inside tissue without causing apparent disease to host. Fresh apple samples from local supermarket, Badulla, were first surface sterilized to limit epiphytic fungi. Potato Dextrose Agar (PDA), supplemented with chloramphenicol (100 mg mL-I) was used to isolate a Penicilium sp. and a Chrysosporium sp. at pH 5.6. Isolated endophytes were cultured in potato dextrose broth for 14 days and extracted with hexane and ethyl acetate successively. Diluted (10 %) diethyl sulfoxide was used to prepare solutions of extracts and inhibition of fungal growth was determined using disc diffusion method at five different concentrations (1000, 2000, 3000, 4000 and 5000 ppm) against Alternaria sp. and Aspergillus sp. with 100 mg mL-1 flucanazole as positive control. Effective concentrations (EC,,, and EC90) were calculated for mean inhibition percentage. Aspergillus sp. growth was highly inhibited compared to Alternaria sp. by Penicllium extract. EtOAc extract of Penicllium showed high inhibition against (Minimum Inhibitory Concentration < 1000 ppm) Alternaria sp. than Crysosporium extracts (MIC 4572.2 ppm). Brine Srimp Lethality Assay (BSLA) was also carried out with 48h old naupali. Results were noted after 24 h. Penicllium sp. extract showed a high lethal toxicity (LC50 402.078 ppm) as they may produce excess of metabolites than Crysosporium sp. The observation of different antifungal activity of the two types of endophytic fungal extracts revealed the variations in chances and rates of producing secondary metabolites. With these results, it can be concluded that, apple endophytic fungal extracts can be used to control selected phytopathogenic fungal species, but the toxicity of extracts should be considered in case of food commodity.
Keywords: Endophytic fungi, Fungal extract, Bioactivities, Malus domestica, Antifungal compounds
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Chemistry, Bioactivities, Technology